<template>
  <div class="nav-bar" :class="{'is_fixed': isFixed}">
    <div class="container">
      <div class="pro-title">
        {{title}}
      </div>
      <div class="pro-param">
        <a href="javascript:;">概述</a><span>|</span>
        <a href="javascript:;">参数</a><span>|</span>
        <a href="javascript:;">用户评价</a>
        <slot name="buy"></slot>
      </div>
    </div>
  </div>
</template>

<script>
export default {
  name: 'nav-bar',
  props: {
    title: String
  },
  data(){
    return {
      isFixed:false
    }
  },
  mounted(){
    window.addEventListener('scroll',this.initHeight)
  },
  methods:{
    // 实现组件吸顶功能
    initHeight(){
      let scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop;
      this.isFixed = scrollTop > 152? true:false;
    }
  },
  // 切换页面销毁组件时，要把绑定在window上的事件清除
  destroyed(){
    window.removeEventListener('scroll',this.initHeight,false)
  }
}
</script>

<style lang="scss">
  @import '../assets/scss/config.scss';
  @import '../assets/scss/mixin.scss';
  .nav-bar {
    height: 70px;
    line-height: 70px;
    border-top: 1px solid $colorH;
    background-color:$colorG;
    z-index: 10;
    &.is_fixed{
      position:fixed;
      top:0;
      width:100%;
      box-shadow: 0 5px 5px $colorE;
    }
    .container {
      @include flex(); 
      .pro-title {
        font-size: $fontH;
        color: $colorB;
        font-weight: bold;
      }
      .pro-param {
        font-size: $fontJ;
        span {
          margin: 0 10px;
        }
        a {
          color: $colorC;
        }
      }
    }
  }
</style>